We Still Don’t Really Know How Effective Medical Marijuana Is

Posted on May 2, 2014

A review of evidence conducted by the American Academy of Neurology found that marijuana has no proven benefit for any neurological disorder besides multiple sclerosis, and that it has significant adverse effects.

For the most part, the lack of documented efficacy is because cannabis has not yet been tested rigorously—or at all—as therapy for such conditions, according to the review by Barbara Koppel, MD, of New York Medical College in New York City, and other members of the AAN’s guideline development panel.

… For MS, the panel found strong evidence that some cannabis products improve subjective perceptions of spasticity and spasticity-associated pain and may also improve some bladder problems.

… There was not much to analyze for any condition other than MS, it turned out.

The study found claims of cannabis efficacy for Huntington’s disease, Tourette’s syndrome, cervical dystonia and epilepsy to be insufficiently supported.

Additionally, reviewers’ persuasion that cannabis products have enough adverse effects to cause clinical concern resulted from an analysis of studies that showed three times as many patients treated with cannabinoids stopped use because of such effects, compared with patients given control substances. Those studies were “mostly vague on the causes for discontinuations” and thus inconclusive, however.

Lead reviewer Barbara Koppel was quoted by MedPage Today as saying, “There’s a place for it [medical marijuana in neurology] and more work is going to need to be done to figure out exactly where.”